Phase separation of a hafnium alkoxide-modified polysilazane upon polymer-to-ceramic transformation—A case study

The polymer-to-ceramic transformation of a hafnium alkoxide-modified polysilazane was investigated via thermogravimetric analysis coupled with in situ mass spectrometry (TG/MS), nuclear magnetic resonance (MAS NMR) and transmission electron microscopy (TEM). The results indicate that the structural evolution of the polysilazane upon ceramization is strongly affected by the modification with hafnium alkoxide. Thus, the content of carbon in the ceramic backbone was relatively low, whereas a large amount of SiN₄ sites and a segregated carbon phase was present in the sample. Furthermore, this study revealed the formation of a SiHfCNO amorphous single phase ceramic via pyrolysis of the polymer at 700 °C, whereas at higher pyrolysis temperatures precipitation of hafnia was observed, leading to an amorphous hafnia/silicon carbonitride ceramic nanocomposite. The precipitation of hafnia was shown to not rely on decomposition processes, but to be a result of rearrangement reactions occurring within the ceramic material.     

An experimental investigation on the influence of phenol on the solubility of CO2 in aqueous solutions of NaOH

Experimental results are presented for the solubility of CO₂ in an aqueous solution of phenol and NaOH (molalties in water: phenol: 0.5; NaOH: 1.0) at (314, 354, and 395) K and pressures up to 10 MPa. The experimental work extends recent investigations on the influence of phenol as well as of (phenol + NaCl) on the solubility of CO₂ in water. In contrast to those previous investigations, the strong electrolyte reacts with carbon dioxide and also with phenol. The experimental results are compared with predictions from a thermodynamic model. That model combines a model for the “chemical” solubility of CO₂ in aqueous solutions of NaOH with a model for the “physical” solubility of CO₂ in aqueous solutions of phenol. An extension is introduced to account for the chemical reaction between the weak acid phenol and the strong base sodium hydroxide. The prediction results nicely agree with the new experimental data. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2832–2840, 2015     

Polyphenolrückgewinnung aus Olivenölabwasser durch Einsatz von Membrantechnologie

Olive mill wastewater (OMW) is obtained as byproduct of oil production in large quantities after the olive harvest, mainly in the Mediterranean region. One problem is the high load of organic matter, such as phytotoxic polyphenols, which causes significant environmental problems. However, due to their antioxidant properties the use of these polyphenols is also popular in several industry branches, e.g. production of plastics, cosmetics and drugs. A combined wastewater treatment permits besides water purification also recovery of the polyphenolic compounds for industrial use. One possibility is membrane technology. An overview of research studies concerning polyphenol recovery from OMW using membrane technologies is given.     

Influence of Membrane Intrusion on Permeate‐Sided Pressure Drop During High‐Pressure Reverse Osmosis

By replacing thermal concentration processes, high‐pressure reverse osmosis has the potential to contribute to cost and energy savings regarding concepts for industrial water reuse. To provide a better understanding of the spiral‐wound element behavior during high‐pressure operation, this study focusses on the investigation of their performance by scrutinizing the crucial effect of the permeate‐sided pressure drop induced by membrane‐spacer interactions. The experiments show a considerable influence of membrane intrusion on the element performance with a strong dependence on the feed pressure.     

An in situ method for measuring acid loss from polymer films

This article reports an in situ approach to studying acid loss from polymer (films of the type used in microlithiography. We developed a method which makes use of the dye coumarin 6 (C6) which has absorption characteristics which change dramatically as a result of acid‐induced changes in its prototropic forms. Acid loss from polymer films containing C6 is accompanied by its deprotonation, which is signaled by a change in the absorption of the film. This technique provides kinetic data describing acid loss from polymer films. Acid loss is a function of both acid volatilization from sites at the surface of the film as well as diffusional processes within the film. Under controlled conditions, acid loss obeys first‐order kinetics, and the half‐lives, τ_1/2, of acids in phenolic and acrylate polymer films were determined. We studied the effects of temperature, acid structure, polymer structure, and T_g on the τ_1/2 values obtained. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1897–1905, 2000     

Nonglycosidic Agonists of Invariant NKT Cells for Use as Vaccine Adjuvants

Based on the crystal structures of human α‐GalCer–CD1d and iNKT–α‐GalCer–CD1d complexes, nonglycosidic analogues of α‐GalCer were synthesized. They activate iNKT cells resulting in dendritic cell maturation and the priming of antigen‐specific T and B cells. Therefore, they are attractive adjuvants in vaccination strategies for cancer and infectious diseases.

     

Spatial distributions of O2, CO2 and SO2 in a pilot-scale fluidized bed combustor operated with different coals

Axial concentration profiles of O₂, CO₂ and SO₂ have been measured at different radial positions in a coal-fired fluidized bed combustor. The profiles show some spatial inhomogeneity in the bed, the degree of which depends on fluidizing velocity and amount of excess air. Comparison of SO₂- with CO₂-concentration profiles reveals that SO₂ is formed in proportion to CO₂ only with anthracite as fuel. With bituminous coals, SO₂ is preferentially formed near the coal feed point. These results are discussed with regard to characteristic times of mixing and chemical reaction in fluidized beds, and SO₂-formation characteristics of the employed coals obtained in a thermobalance.     

Simultaneous measurement of weight loss by DTG combustion and SO2-formation for different coals

Burning profiles and SO₂-formation profiles were measured simultaneously for four different coals by slowly heating coal samples in a flow of air in a thermobalance. The profiles of weight loss and SO₂ formation have the same shape with anthracite combustion. The SO₂-formation profiles of bituminous coals usually display two peaks that approximately correspond to the release of volatile matter and combustion of char in the burning profiles. No correlations could be found between either the types of sulphur present in the raw coals or the ratio of volatile matter to fixed carbon and the shape of the SO₂-formation profiles for the bituminous coals.